title: Formation and biliary excretion of glutathione conjugates of bile acids in the rat as shown by liquid chromatography/electrospray ionization-linear ion trap mass spectrometry.
abstract: Acyl-adenylates and acyl-CoA thioesters of bile acids (BAs) are reactive acyl-linked metabolites that have been shown to undergo transacylation-type reactions with the thiol group of glutathione (GSH), leading to the formation of thioester-linked GSH conjugates. In the current study, we examined the transformation of cholyl-adenylate (CA-AMP) and cholyl-coenzyme A thioester (CA-CoA) into a cholyl-S-acyl GSH (CA-GSH) conjugate by rat hepatic glutathione S-transferase (GST). The reaction product was analyzed by liquid chromatography (LC)/electrospray ionization (ESI)-linear ion trap mass spectrometry (MS). The GST-catalyzed formation of CA-GSH occurred with both CA-AMP and CA-CoA. Ursodeoxycholic acid, lithocholic acid, and 2,2,4,4-(2)H4-labeled lithocholic acid were administered orally to biliary fistula rats, and their corresponding GSH conjugates were identified in bile by LC/ESI-MS2. These in vitro and in vivo studies confirm a new mode of BA conjugation in which BAs are transformed into their GSH conjugates via their acyl-linked intermediary metabolites by the catalytic action of GST in the liver, and the GSH conjugates are then excreted into the bile.
authors.affiliation: Faculty of Pharmaceutical Sciences, Kinki University, Higashi-Osaka 577-8502, Japan.
authors.forename: Kuniko
authors.initials: K
authors.lastname: Mitamura
authors.forename: Saai
authors.initials: S
authors.lastname: Watanabe
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Mitsumoto
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Sakai
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sogabe
authors.forename: Tateaki
authors.initials: T
authors.lastname: Wakamiya
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ikegawa
mesh_terms: D000214:Acyl Coenzyme A / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001646:Bile / Q000737:chemistry*; D001647:Bile Acids and Salts / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D002853:Chromatography, Liquid; D005978:Glutathione / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000214:Acyl Coenzyme A; D001647:Bile Acids and Salts; D005978:Glutathione